Document feeding device

ABSTRACT

The present disclosure describes apparatus and techniques for creating a high-speed singulated flow of documents, such as mail pieces from a stack of said documents, in order that they may be subsequently identified and sorted to their proper destinations. The problem of double-feeding is virtually eliminated by the multiple restraint schemes provided by the present feeder. In particular, the device incorporates means whereby the documents to be processed are made to enter a channel formed between moving feed belts and a pivoting gate. The latter forms an extension of the registration wall along which documents to be fed are aligned, and incorporates within itself vacuum braking means. The pivoting gate member provides both a barrier restraint and a frictional restraint which act concurrently on the second or double document to stop it as it moves toward the conveyor transport system along with the document desired to be fed out of the stack.

United States Patent [1 1 Wojtovviea et al.

[ Nov. 12, 1974 1 DOCUMENT FEEDING DEVICE [73] Assignee: Burroughs(Zorporation, Detroit,

Mich.

[221 Filed: Nov. 30, 1973 [21] Appl. No.: 420,718

[52] US. Cl 271/11, 271/34, 271/104, 271/167 [51] Int. Cl B6511 5/08[58] Field of Search 271/11, 104, 106, 34, 137, 271/121, 167; 209/73Primary Examiner-Allen N. Knowles Attorney, Agent, or Firm-Francis A.Varallo; Edward J. Feeney, Jr.; Edward G. Fiorito [57] ABSTRACT Thepresent disclosure describes apparatus and techniques for creating ahigh-speed singulated flow of documents, such as mail pieces from astack of said documents, in order that they may be subsequentlyidentified and sorted to their proper destinations. The problem ofdouble-feeding is virtually eliminated by the multiple restraint schemesprovided by the present feeder. In particular, the device incorporatesmeans whereby the documents to be processed are made to enter a channelformed between moving feed belts and a pivoting gate. The latter formsan extension of the registration wall along which documents to be fedare aligned, and incorporates within itself vacuum braking means. Thepivoting gate member provides both a barrier restraint and a frictionalrestraint which act concurrently on the second or double document tostop it as it moves toward the conveyor transport system along with thedocument desired to be fed out of the stack.

9 Claims, 2 Drawing Figures slam/L383 PATENTED NOV 12 I974 SHEEYIOF 2DOCUMENT FEEDING DEVICE CROSS REFERENCE TO RELATED APPLICATIONSreferenced herein. The latter application and the present one areassignedto a common assignee. Certain prior art techniques in documentsingulation are also found in Canadian Pat. No. 567,020, Paper-HandlingApparatus," by P. H. Wendt, et al., and this patent is referred tohereinafter.

BACKGROUND OF THE-INVENTION reference Canadian patent a mechanism isprovided on one side of the stack of documents which applies a suctionor opposing vacuum pressure thereto in order to prevent more than onedocument from being drawn upward by the primary vacuum force associatedwith'the feed drum. However, multiple feeds still occur with this typeof feeder because the high strength of the primary force utilizedresults ina bleed-through force capable of attracting multiplerelatively porous documents. Obviously documents having perforationstherein, such as checks, are highly susceptible to multiple feeds. Moreover, the opposing vacuum force affecting the docu-' ments residing inthe stack prior to feeding is ofteninsufficient to separate thosedocuments clinging to each other by'adhesive and electrostatic forces.

The present invention virtually eliminates the problem of multiplefeedsby utilizing combined barrier and vacuum braking restraints which haltthe second or double document after it has left the stack and before itcan contact the transport means toward which it is being driven by thefeeder belts.

SUMMARY OF THE INVENTION In accordance with the present invention, theproblem of multiple-feeds inherent in high vacuum systems is solved byproviding a channel between the moving feeder belts and a pivoting gate,which is an extension of the side registration wall along which thedocuments waiting to be fed are aligned. The width of theehannel ischosen such that the gate acts as a barrier to a double documentattempting to exit the feeder. The primary feeder vacuum drives thedocument to be fed along with the double to the gate where thelatterpivots, if necessary, just enough to strip the double from thedocument being fed. This pivoting actionalso permits single documents ofgreater width than the aforementioned channel to exit the feeder. Thebarrier restraint is augmentedby vacuum singulation provided by thepivoting gate itself. Thus, the gate forms a vacuum chamber supplied bythe primary feeder vacuum which exerts a secondary vacuum force,considerably less than the primary force, upon the documents passingadjacent thereto. This secondary force while producing only a negligibleeffect upon a single document under control of the primary force, isnevertheless sufficient to brake to a stop and separate any doubledocument from the document being fed.

Other features and advantages of the present invention will becomeapparent in the appearing hereinafter.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a plan view of the documentfeeder. FIG. 2 depicts a vertical elevation of the feeder as viewed fromthe rear.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 depicts the basicelements which make up the feeder device of the present invention. Astack of documents 10 which may be mail pieces are depicted in positionto be fed by the feeder. The arrow 12 indicates the directionof feed ofthe documents being processed. It may be assumed that .the documentshave arrived at the point shown in FIG. 1 by virtue of a stack advancesystem, such as that described in the reference copending applicationSer. No. 365,475. In accordance with the techniques taught in the latterapplication, the stack advance has been halted through the operation ofthe stack sensing switch actuators Hand 16. The documents 10 waiting tobe fed are generally edged against registration wall 15 and are beingrestrained from con-, tac'ting the feeder belts 18 by pusher fingers 20.Air flow created by a blower system (not shown) and routed to the feederhousing 22 which includes a vacuum chamber, exerts a vacuum pressure onthe document waiting to be fed which pulls it against the pushercontinued reference to FIG. 1, the vacuum pressure ex- I erted on thefirst document flexes a portion of the document about a pivot pointlocated at the buffer plate 30. The buffer plate prevents contact of thedocument with the moving belts until substantially the entire angle hasbeen traversed. This prevents any premature motion of the document inthe direction of arrow 12. Once the flexure angle has been attained, thedocument contacts the moving feeder belts 18. These belts are perforatedwith a square hole pattern 32 (as seen in FIG. 2) which appears toprovide an optimum driving force for the document being fed. The beltsare contiguous with the face of the vacuum chamber and air entering thechamber passes through the belt perforations. The document forcedagainst the feeder belts isaccelerated in the direction of arrow 12. Thebelts are driven by pulleys 34 (as seen in FIG. 2), while idlers 36 and38 (FIG. 1) provide the'geometry for proper contact with the face of thevacuum chamber.

The moving document is now made to enter a channel 40 of minimumdimension A which is formed bedetailed description tween the movingfeeder belts l8 and a pivoting gate 42 which is a substantially coplanarextension of the inner surface of registration wall 18 and providesvacuum singulation. The vacuum pressure for the gate singulator 42 maybe derived from the main feeder vacuum chamber in housing 22 through theuse of a flexible tube 43 coupling ports 44 and 46. Also as indicated,the singulator has the capability of pivoting in order to increase thechannel 40 dimension A. The pivoting takes place in the direction ofarrow 48 about point 50. Tension spring 52 permits the singulator 42 toreturn to the position shown, after a document is fed. The purpose ofthe singulator is to exert a small forcevia port 53 on a doubleddocument to prevent its entry in the acceleration rollers 54. Thechannel dimension is chosen to be such that the working face of thesingulator will be in close proximity to a double document attempting toleave the feeder. For example, a dimension of approximately 0.150 incheshas proved satisfactory in an actual operative embodiment for handlingmail pieces. Single documents of thicknesses approaching the selectedminimum channel dimension also contact the singulator 42, and in thisspecial case the singulator acts to slightly retard the acceleration ofthe document. Although this would seem to be a detrimental effect, theoverall effect is negligible because the gate singulator vacuum force ismuch smaller than the main driving force of the feeder vacuum chamber.

Since the minimum channel dimension A is chosen to be less than themaximum single document thicknessexpected to be processed, documentsthicker than the minimum channel dimension must increase the channelwidth in order to exit the feeder. The force of the vacuum appliedthrough feeder belts drives the document against the singulator gate 42,compressing spring 52 to a point which permits passage of the document.The pivoting action creates a stripping action-which acts in a manner toseparate double documents. In effect, the pivoting gate 42 creates abarrier restraint which in itself is a singulation method and enhancesor augments the frictional restraint supplied by the vacuum singulator.

Once the feeder has advanced the document to the acceleration rollers54, the pusher fingers 20 are required to be extended to inhibit thefeeding of succeeding documents until the system is capable ofprocessing them. This return motion is supplied by return spring 56(FIG. 2) located in proximity to the rotary solenoid coupling 28. Whenthe solenoid 24 is energized to retract the fingers, this spring isextended. Deenergization of the solenoid permits the spring energy toreturn the fingers to their extended condition. With specific referenceto FIG. 1, the de-energization of the solenoid 24 is effected by thedocuments leading edge as it breaks the light beam from lamp 58 directedtoward photocell 60. The photocell 60 is positioned such that the lightbeam is interrupted only when the document has entered the accelerationrollers 54. The document must be under control of therollers before itis stripped from the feeder belts by the extension of pusher fingers 20.

In the-elimination of double feeds by the use of vacuum singulation in apivoting gate member, certain geometric aspects of the feeder design areof interest. With reference to FIG. 1, the dimension B, the distancefrom the point of common tangency of rollers 54 to the inner surface ofregistration wall is significant.

The larger dimension B is made, the more effective the vacuum singulatorgate 42 becomes, since more time is available for the vacuum retardingforces to operate on the doubled document. Documents halted by thesingulator, are permitted to enter the transport system on the next feedcycle. Since these documents are already partially singulated from therest of the stack, the probability of doubling on this last mentionedcycle is very small.

The maximum length of dimension B is determined by the dimension C whichas seen in FIG. I is the distance from the acceleration rollers 54 tothe end of the vacuum chamber in housing 22. This last dimension must begreater than the minimum length document. If it is not, pickup of morethan one document during a feed cycle is possible before effectiveinhibiting by fingers 20 can take place.

Another geometrical aspect of importance is dimension D, FIG. 1. This isthe distance from the closest edge of the vacuum chamber orifice to theregistration wall 15. This dimension is significant in respect toinitially mis-registered documents. The greater dimension D is, the lesslikely that two documents will overlap the vacuum chamber and beaccelerated out together, creating a double. In general, dimension D isdesigned to be a maximum within the constraints of dimension C (not toexceed the minimum document length) and dimension E (adequate to obtainthe requiredacceleration forces for a specified feed rate).

In summary, it is'apparent that the more restraint schemes thatdocuments are exposed to in the feeding process, the lower the doublesrate and the more effective the processof singulation. The feederdescribed herein has registered an extremely low doubles rate in actualoperating tests as a result'of the multiple restraints incorporatedtherein.

First, the pivoting gate portion of the registration wall functions as abarrier restraint. Vacuum bleed through forces are not great enough on adouble document to permit it to open the spring loaded pivoting wall.However, a thick single document when acted upon by the primary feedervacuum forces is capable of pivoting the gate to enlarge the exitchannel.

Second, the vacuum braking force within the pivoting gate, causes africtional restraint to be imposed upon the double document. The brakingforce is of such strength that it is able to stop the document at apoint past the registration wall but before it can enter theacceleration rollers of the transport system. By virtue of the vacuumforce and the coefficient of friction,

the brake prevents the second document from moving with the documentdesired to be fed.

Finally, a gravity restraint is present as a result of the backward tiltcondition'(the top edge of the'document being displaced backward fromthe bottom edge) induced in the document stack by the initial biasing ofthe documents and the application of the sensing switches as taught inthe reference copending application. When the first document is drawnagainst the feeder face by the primary vacuum force, a lesser force,perhaps due to a transient partial vacuum generated between the firstand second document tends to cause the latter to move with the former.The gravity restraint on the second tilted-back document is greater thanthe aforementioned partial vacuum force, and the second document remainsin place.

If the stack assumes a forward tilt geometry, the frictional resistanceto movement of the lower edge of the document to the feeder face isovercome by the primary feeder vacuum force in the case of the firstdocument, but such frictional restraint prevents movement of the seconddocument along with the first.

in conclusion, the inventive concepts and implementations describedherein have proved highly satisfactory in actual operative systems inwhich the doubles rate experienced in actual tests was approximately 0.2percent. It should be understood that changes and modifications of thefeeder may be needed to suit particular requirements. Such changes andmodifications insofar as they are not departures from the true scope ofthe invention, are intended to be covered by the claims appended hereto.

What is claimed is:

l. A document feeding device comprising:

a feeder vacuum chamber operatively connected to generate an area of lowatmospheric pressure adja-. cent a face portion thereof, v

at least a single moving perforated feed belt operatively connected tocontiguously traverse said face portion of said feeder vacuum chamber,

a registration wall situated in predetermined angular relationship tothe face portion of said feeder vacuum chamber for enabling substantialalignment of the forward edges of the documents prior to their beingfed,

a gate member pivotally mounted to provide a substantially coplanarextension of said registration wall, the face portion of said gatemember being positioned in close proximity to said moving feed belt andforming therewith a channel through which said documents to be fed aredriven by said belt, said gate member acting as a barrier restraint upona double document to impede its exit from the feeder,

said gate member including additional vacuum chamber means operativelyconnected to generate an area of low atmospheric pressure adjacent itsface portion, the gate member vacuum force acting as a frictionalrestraint upon said double document to impede its exit from the feeder,said barrier and frictional restraints being exerted concurrently onsaid double document by said gate member to effectively prevent theuntimely feeding of said double document.

2. A document feeding device as defined in claim 1 further characterizedin that the vacuum force present at the face portion of the gate vacuumchamber is less than that present at the face portion of said feedervacuum chamber.

3. A document feeding device as defined in claim 2 wherein the minimumdimension of said channel is approximately the average width of thedocuments being fed.

4. A document feeding device as defined in claim 3 further including atension spring coupled to said gate member and biased to pivot saidmember in a direction to maintain a predetermined minimum channeldimension.

5. A document feeding device as defined in claim 4 further including apair of acceleration rollers located downstream from said gate memberfor receiving in turn the documents being driven thereto by said feedbelt.

6. A document feeding device as defined in claim 5 wherein said vacuumchambers are coupled to each other by a flexible tube, whereby thevacuum pressure for said gate vacuum chamber is derived from that ofsaid feeder vacuum chamber.

7. A document feeding device as defined in claim 6 further characterizedin that said feed belt is perforated in a square hole pattern tooptimize the vacuum driving force applied to said documents.

8. A document feeding device as defined in claim 7 wherein saiddocuments are mail pieces and said minimum channel dimension isapproximately 0. inches.

9. A document feeding device as defined in claim 8 further including aplurality of pusher fingers positioned adjacent said face portion ofsaid feeder vacuum chamber and being intermeshed with said feed belt,

tion permitting contact therewith.

l= l l

1. A document feeding device comprising: a feeder vacuum chamberoperatively connected to generate an area of low atmospheric pressureadjacent a face portion thereof, at least a single moving perforatedfeed belt operatively connected to contiguously traverse said faceportion of said feeder vacuum chamber, a registration wall situated inpredetermined angular relationship to the face portion of said feedervacuum chamber for enabling substantial alignment of the forward edgesof the documents prior to their being fed, a gate member pivotallymounted to provide a substantially coplanar extension of saidregistration wall, the face portion of said gate member being positionedin close proximity to said moving feed belt and forming therewith achannel through which said documents to be fed are driven by said belt,said gate member acting as a barrier restraint upon a double document toimpede its exit from the feeder, said gate member including additionalvacuum chamber means operatively connected to generate an area of lowatmospheric pressure adjacent its face portion, the gate member vacuumforce acting as a frictional restraint upon said double document toimpede its exit from the feeder, said barrier and frictional restraintsbeing exerted concurrently on said double document by said gate memberto effectively prevent the untimely feeding of said double document. 2.A document feeding device as defined in claim 1 further characterized inthat the vacuum force present at the face portion of the gate vacuumchamber is less than that present at the face portion of said feedervacuum chamber.
 3. A document feeding device as defined in claim 2wherein the minimum dimension of said channel is approximately theaverage width of the documents being fed.
 4. A document feeding deviceas defined in claim 3 further including a tension spring coupled to saidgate member and biased to pivot said member in a direction to maintain apredetermined minimum channel dimension.
 5. A document feeding device asdefined in claim 4 further including a pair of acceleration rollerslocated downstream from said gate member for receiving in turn thedocuments being driven thereto by said feed belt.
 6. A document feedingdevice as defined in claim 5 wherein said vacuum chambers are coupled toeach other by a flexible tube, whereby the vacuum pressure for said gatevacuum chamber is derived from that of said feeder vacuum chamber.
 7. Adocument feeding device as defined in claim 6 further characterized inthat said feed belt is perforated in a square hole pattern to optimizethe vacuum driving force applied to said documents.
 8. A documentfeeding device as defined in claim 7 wherein said documents are mailpieces and said minimum channel dimension is approximately 0.150 inches.9. A document feeding device as defined in claim 8 further including aplurality of pusher fingers positioned adjacent said face portion ofsaid feeder vacuum chamber and being intermeshed with said feed belt,said pusher fingers being capable of assuming either of two positionscomprising respectively an extended position above and a retractedposition below the surface of said feed belt, the former positioninhibiting contact of the document with said feed belt, and the latterposition permitting contact therewith.